The aim of this research is to develop improved permanent soft denture lining materials based on new methacrylic siloxane resins. The backbone polymer polysiloxane provides the silicone elastomer characteristics. The methacrylate groups located on the polymer chains provide the crosslinking and copolymerization sites. The polymer undergoes free- radical addition polymerization and crosslinking upon application of heat, light or chemicals. Hardness, tensile strength, per cent elongation, the bonding strength to denture base polymer, and water sorption of the new lining materials will be determined and compared with those of commercial soft lining materials. The new lining materials are expected to have enhanced resiliency, good bonding to the denture base, and minimum chemical degradation and water sorption. PROPOSED COMMERCIAL APPLICATION Potential commercial applications of the research is the development of improved permanent soft denture liners which have permanent resiliency, good adhesion to denture base polymers, minimum water sorption and solubility, and adequate wettability in the oral environment.